This invention relates to microstrip antennas and more particularly to a plurality of radiating elements in an array wherein only one element is fed to excite the fed element directly and parasitically excite all the other elements for providing a high gain end fire antenna array.
Previously, it has been necessary to feed each of several microstrip elements with a separate coaxial connector to provide a high gain end fire antenna array. Phase shifters were also required in the separate coaxial lines feeding each of the separately fed elements. This required more space and expense, and complicated the conformal arraying capability of such an antenna especially where it was to be flush mounted on an airfoil surface. It also was necessary to use many more excited elements to provide as high a gain as obtained with the antenna in this invention.
U.S. Pat. No. 3,978,487, by Cyril M. Kaloi, discloses a side-by-side coupled fed microstrip antenna. That antenna differs greatly from the present electrically end-to-end coupled parasitic antenna disclosed herein, in that in the previous Coupled Fed Antenna two elements are coupled magnetically (i.e., magnetic field coupling) side-by-side; only one element is excited to radiate; the feedpoint is at the edge of the nonradiating coupler element; and, there is no end fire mode of radiation.